Fill sheets and related fill pack assemblies

ABSTRACT

A fill sheet for cooling heat transfer fluid in a cooling tower includes an air intake end, an air outlet end, a top edge and a bottom edge. The air outlet end is positioned opposite the air intake end along a lateral axis. The top edge connects the air intake end and the air outlet end and the bottom edge also connects the air intake end and the air outlet end. The bottom edge is positioned opposite the top edge along a vertical axis. A plurality of flutes extends generally parallel to the lateral axis between the air intake end and the air outlet end. An offset extends generally parallel to the vertical axis. A first flute of the plurality of flutes transitions from a first peak at a first side of the offset to a first valley at a second side of the offset.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication No. 62/951,365, filed on Dec. 20, 2019 and titled “FillSheets and Related Fill Pack Assemblies,” the entire contents of whichis incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

A variety of film fills and fill sheets are available for cross-flowcooling towers that may be assembled together into fill packs. In orderto distinguish and create advantages in the marketplace, it is importantfor a fill manufacturer to offer a product with improvements overcompeting fill options. Some examples of these advantages includeimproved tower performance through a higher efficiency fill, ease ofinstallation, product longevity, product cost, and reduction of driftexiting the fill.

The performance of a cooling tower can be characterized by the quantityof water or other cooling fluid that can be cooled to a specifiedoperating temperature for a certain set of ambient conditions. In orderto achieve this cooling, water is sprayed onto the cooling tower filland is exposed to an air flow, thereby causing evaporation of a smallportion of water into the air, which cools the remaining water. Byincreasing the amount of evaporation occurring within the cooling tower,the overall performance of the tower may also be increased or improved.Since most of this evaporation occurs within the fill, changes to thefill design can significantly impact the amount of cooling a tower canachieve during operation. Specifically, changes to a cooling tower fillthat reduce the pressure drop across a fill for a given air flow orotherwise improve the thermal performance of the fill, will result in abetter performing cooling tower. By reducing the pressure drop across afill, the resistance to airflow through the tower is decreased, allowingmore air to pass over the water film for the same fan power, therebycausing the amount of evaporation to increase. To improve the thermalperformance of a fill, increased mixing of the air and water canincrease the amount of evaporation of water into the air by improvingthe conditions at the air-water interface. Generating mixing of the air,however, typically requires changes to the fill which also increases thepressure drop across the fill, indicating the need for fill designswhich can either reduce pressure drop over existing designs with minimalimpact to mixing or improved strategies for mixing which require equalor less pressure drop.

For cross-flow cooling towers, film fills are installed in the tower asa hanging fill, or as a bottom supported fill. For hanging fills, holesare punched near the top of the fill sheets to accept rails or formounting on rails where the fill sheets are spaced along the length ofthe rails. This causes the individual fill sheets to be under tensileloading under the holes, but under compressive loading at the rail-sheetinterface. For bottom supported fills, sheets are secured together intorigid blocks of fill, then placed on top of a support structure in thetower. Typically, bottom supported fills are easier to install intotowers than hanging fills but the bottom supported fill sheets requireadditional structural features to resist the compressive loading seenduring use, particularly during operation under loading from the wateror other cooling fluid utilized in the tower or from the accumulation ofexternal deposits, such as ice, biological foulants, scale or relatedother accumulated deposits that all apply additional weight and forcesonto the fill. These structural features of the fill sheets, such asstructural ribs or glue boss features, usually provide little to nothermal benefit for the fill and increase the pressure drop, therebyresulting in reduced tower performance. Alternative to the structuralribs and glue bosses, thicker gauge sheets may be used for the fillconstruction, however the increase in gauge thickness increases thetotal cost of the fill by adding more material to each fill sheet.

For film fills used in cross-flow towers, all fills contain a dedicatedheat transfer area, while some also contain an integral drift eliminatornear the air outlet of the fill and/or a louver section near the airinlet of the fill. The heat transfer area of the fill is responsible forthe thermal performance of the fill by providing a large surface areafor water to spread out on the surfaces of the fill to increase contactwith the air, mixing the air as it flows through the fill and mixing thewater film as it flows over the sheets, while maintaining a low pressuredrop across the fill. Typically, the heat transfer surface forcross-flow fills consists of fluted fill sheets with small surfacefeatures (microstructure) patterned across the surface or fill sheetswith more aggressive patterned features and less pronounced flutefeatures. For fills with flutes, the flutes are usually continuousacross the heat transfer area or have a generally constant cross-sectionalong their length and are commonly cross corrugated, although may beoriented horizontally or vertically.

Although most of the bulk water adheres to the surface of a film fill,some of the water forms small droplets and escapes the fill through theair outlet, otherwise known as drift. Drift is undesirable, as the driftrepresents a loss of water or other cooling fluid from the system andthe loss of water or other cooling fluid has a cost to replenish, bothitself and any treatment chemicals contained within the cooling fluid.The drift may also have a deleterious impact on surrounding equipmentand environments since the drift may contain chemicals, salts andbacteria present in the circulating water or fluid. For cross-flow towerfilm fills, drift elimination features are sometimes included on the airoutlet side of the sheet to capture these drift droplets and preventthem from escaping the cooling tower, which are referred to as drifteliminators and may be comprised of integral drift eliminators (“IDs”).For cross-flow film fills, there are typically two different types ofdrift eliminators which may be integrated, including the tube drifteliminator and the blade drift eliminator. Generally, tube drifteliminators are angled tubes formed into the ID section of the fill byaligning drift corrugations of adjacent sheets. As water droplets enterthe tubes entrained in the air stream, the momentum of the dropletscauses them to impact the tube wall as the airflow changes directionwhile following the angled tube of the ID. A vertical channel istypically included at the inlet of the integral drift eliminator tubesto allow water collected on the surface of the integral drift eliminatorto drain out of the fill into a lower catch basin, and to providevertical structural support for bottom supported fills. One limitationof current implementations of this type of drift eliminator isintroduced when water reaches the tube inlet of the eliminator. Whenwater reaches the transition between the tube section and the drain,some water may be pushed along part of the top wall of the tube by theair before falling off into the air stream. By introducing dropletsfarther into the eliminator, it becomes easier for these droplets toescape out of the eliminator without impacting a wall, thereby reducingeliminator performance. Integral blade drift eliminator designsaccomplish drift removal by creating a large vertically oriented ridge,near the air outlet of the fill to change the direction of airflow. Themomentum of the water droplets at the integral drift eliminator inletcauses an impact with the ridge walls, eliminating the drift from theairstream. Other structural features such as ribs or spacers may beincluded before or after the eliminator ridge to ensure the sheetsremain separated during operation and to stiffen the fill and/or sheet,as well as the assembled fill pack.

At the air inlet of the fill, integral louvers are sometimes includedinto the fill design to prevent water from splashing out of the front ofthe fill. These integral louvers are usually comprised of corrugationswhich are angled downward as they protrude into the fill, to provide asloped surface for the water to run down, thereby preventing water orother cooling fluid from reaching the front of the fill. Thecorrugations on each sheet may be assembled together to form tubes orremain parallel to adjacent sheet corrugations with additional sheetspacer features added to the design.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the preferred invention is directed to a fill sheet forcooling a heat transfer fluid in a cooling tower when assembled intofill packs comprised of pluralities of fill sheets for use in across-flow cooling tower. The fill sheet includes an air intake end, anair outlet end positioned opposite the air intake end along a lateralaxis, a top edge connecting the air intake end and the air outlet endand a bottom edge connecting the air intake end and the air outlet end.The bottom edge is positioned opposite the top edge along a verticalaxis. The heat transfer fluid is configured for flowing between the topedge and the bottom edge. A plurality of flutes extends generally alongthe lateral axis between the air intake end and the air outlet end. Anoffset or transition feature provides a flat section of macrostructureand extends generally parallel to the vertical axis. A first flute ofthe plurality of flutes transitions from a first peak at a first side ofthe offset to a first valley at a second side of the offset. The offsetor transition feature includes a rib extending generally parallel to thevertical axis and a spacer to provide structural support for the offset.Microstructure is preferably integrally formed into the offset and has agenerally herringbone shape. The spacer is preferably comprised of afirst plurality of spacers, wherein each of the plurality of flutesincludes one of the first plurality of spacers positioned thereon at theoffset or transition feature. The rib is preferably comprised of anintermediate rib, including a first intermediate rib and a secondintermediate rib and the spacer is comprised of an intermediate columnof spacers.

In another aspect, the preferred invention is directed to a fill sheetfor cooling heat transfer fluid in a cooling tower when arranged intofill packs comprised of pluralities of fill sheets. The fill sheetincludes an air intake end, an air outlet end positioned opposite theair intake end along a lateral axis, a top edge connecting the airintake end and the air outlet end and a bottom edge connecting the airintake end and the air outlet end. The bottom edge is positionedopposite the top edge along a vertical axis. A plurality of spacersextends from a heat transfer area of the fill sheet between the airintake end, the air outlet end, the top edge and the bottom edge. Theplurality of spacers includes a first spacer having a first head end anda first tail end. The first head end is positioned closer to the topedge than the first tail end. The first spacer defines a first spaceraxis. The first spacer axis defines a first acute spacer angle with thelateral axis. The plurality of spacers includes a second spacer having asecond head end and a second tail end. The second head end is positionedcloser to the top edge than the first tail end. The second spacerdefines a second spacer axis. The second spacer axis defines a secondacute spacer angle with the lateral axis. The first spacer axis extendsat an opposite side of the vertical axis relative to the second spaceraxis.

In yet another aspect, the preferred invention is directed to a fillpack for cooling heat transfer fluid in a cooling tower. The fill packincludes a first fill sheet having a first top edge, a first bottom edgeand a first heat transfer area between the first top edge and the firstbottom edge and a second fill sheet having a second top edge, a secondbottom edge and a second heat transfer area between the second top edgeand the second bottom edge. A first plurality of spacers extendsgenerally perpendicularly relative to a first sheet plane from the firstfill sheet. The first plurality of spacers includes a first spacerhaving a first head end and a first tail end. The first head end ispositioned closer to the first top edge than the first tail end. Asecond plurality of spacers extends generally perpendicularly relativeto a second sheet plane from the second fill sheet. The second pluralityof spacers includes a second spacer having a second head end and asecond tail end. The second head end is positioned closer to the secondtop edge than the second tail end. The first head end is positionedproximate the second head end in an installed configuration. A verticalaxis is defined generally perpendicularly relative to the first andsecond top edges and the first and second bottom edges. The first tailend extends toward an opposite side of the vertical axis relative to thesecond tail end.

In a further aspect, the preferred invention is directed to a fill packfor cooling heat transfer fluid in a cooling tower. The fill packincludes a first fill sheet having a first air intake side, a first topedge, a first air outlet side and a first heat transfer area between thefirst air intake side and the first air outlet side and a second fillsheet having a second air intake side, a second top edge, a second airoutlet side and a second heat transfer area between the second airintake side and the second air outlet side. An integral drift eliminatoris associated with the first and second air outlet sides in an installedconfiguration. The drift eliminator defines a plurality of tubes with adrift eliminator inlet positioned proximate the first and second heattransfer areas and a drift eliminator outlet spaced away from the firstand second heat transfer areas. The plurality of tubes extends generallytoward the first and second top edges from the drift eliminator inlettoward the drift eliminator outlet. Each of the plurality of tubesincludes a blocking structure on each of the plurality of tubes at thedrift eliminator inlet configured to block a film of the heat transferfluid at the drift eliminator inlet to promote droplet formation anddirect the heat transfer fluid back into the heat transfer area.

In an additional aspect, the preferred invention is directed to a fillsheet for cooling heat transfer fluid in a cooling tower when assembledinto fill packs comprised of pluralities of fill sheets. The fill sheetincludes an air intake end, an air outlet end positioned opposite theair intake end along a lateral axis, a top edge connecting the airintake end and the air outlet end and a bottom edge connecting the airintake end and the air outlet end. The bottom edge is positionedopposite the top edge along a vertical axis. A microstructure is formedon the fill sheet. A support rib extends between the top edge and thebottom edge. The support rib includes a first support rib and a secondsupport rib. The first and second support ribs are spaced laterally fromeach other along the lateral axis and extend substantially parallel tothe vertical axis. The support rib has a first support rib portionhaving a first support rib length. The first support rib includes afirst rib height and the second support rib including a second ribheight. The microstructure has a microstructure height. The first ribheight is less than the microstructure height in the first support ribportion and the second rib height is greater than the microstructureheight in the first support rib portion. The support rib is preferablycomprised of an outlet side rib positioned proximate the air outlet end.The first support rib portion preferably has a first support rib portionlength. In the preferred embodiment, the first rib height may becomprised of a rib minimum height and the second rib height may becomprised of a rib maximum height with the rib height transitionsbetween the rib maximum heights and the rib minimum heights.

In a further aspect, the preferred present invention is directed to afill sheet for cooling heat transfer fluid in a cooling tower whenassembled into fill packs comprised of pluralities of fill sheets. Thefill sheet includes an air intake end, an air outlet end positionedopposite the air intake end along a lateral axis, a top edge connectingthe air intake end and the air outlet end and a bottom edge connectingthe air intake end and the air outlet end. The bottom edge is positionedopposite the top edge along a vertical axis. A plurality of ribspositioned generally between the air intake end and the air outlet end.An intermediate rib is positioned generally between the air intake endand the air outlet end. The intermediate rib includes a firstintermediate rib and a second intermediate rib. The first intermediaterib extends from a top end proximate the top edge to first end. Thesecond intermediate rib extends from a bottom end proximate the bottomedge to a second end. The second rib includes the second end and a thirdend. The first end is positioned proximate the second end. An offsetextends generally parallel to the vertical axis. A first flute of aplurality of flutes transitions from a first peak at a first side of theoffset to a first valley at a second side of the offset. Theintermediate rib is positioned at the offset. The first end of the firstrib is positioned proximate the second end of the second rib. At leastone of the first and second ribs are intersected by the lateral axisbetween the top end and the third end. The first and second ribs arepreferably spaced at a lateral spacing that is between one-quarter andtwo inches (¼-2″). The first and second ribs of the preferredembodiments may be comprised of any one of intake side ribs, outlet sideribs or intermediate ribs. The first rib may be comprised of a firstintermediate rib segment and the second rib may be comprised of a secondintermediate rib segment, therein a first end and a second end arepositioned proximate a middle of the fill sheet in the preferredembodiment.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe invention, will be better understood when read in conjunction withthe appended drawings. For the purpose of illustrating the invention,there are shown in the drawings embodiments which are presentlypreferred. It should be understood, however, that the invention is notlimited to the precise arrangements and instrumentalities shown. In thedrawings:

FIG. 1 is a front elevational view of a fill sheet in accordance with afirst preferred embodiment of the present invention;

FIG. 1A is a magnified front perspective view of a portion of the fillsheet of FIG. 1 , taken from within shape 1A of FIG. 1 ;

FIG. 1B is a side perspective view of the fill sheet of FIG. 1 , takenalong the line 1B-1B of FIG. 1 ;

FIG. 1C is a wireframe front perspective view of a portion of the fillsheet of FIG. 1 , representing undulating flutes and offsets of the fillsheet;

FIG. 2 is a bottom perspective view of a portion of an air outletsection of the fill sheet of FIG. 1 , taken generally rearwardly of theline 2-2 of FIG. 1 ;

FIG. 2A is a front elevational view of the portion of the air outletsection of the fill sheet of FIG. 2 ;

FIG. 2B is a cross-sectional view of a portion of the fill sheet of FIG.1 , taken along line 2B-2B of FIG. 2 ;

FIG. 2C is a cross-sectional view of a portion of the fill sheet of FIG.1 , taken along line 2C-2C of FIG. 2A;

FIG. 2D is a cross-sectional line view of the fill sheet of FIG. 1 ,taken along line 2D-2D of FIG. 2 ;

FIG. 3 is a bottom plan view of a pair of fill sheets of FIG. 1installed or assembled together to define a fill pack;

FIG. 3A is a cross-sectional line view of the fill pack of FIG. 3 ,taken along line 3A-3A of FIG. 3 ;

FIG. 3B is a cross-sectional line view of the fill pack of FIG. 3 ,taken along line 3B-3B of FIG. 3 ;

FIG. 3C is a cross-sectional line view of the fill pack of FIG. 3 ,taken along line 3C-3C of FIG. 3 ;

FIG. 4 is a magnified bottom plan view of a portion of the fill pack ofFIG. 3 , wherein spacers of the fill sheet are shown in an installed orassembled configuration;

FIG. 5 is a front elevational representation of the shapes of thespacers of FIG. 4 ;

FIG. 6 is a front elevational representation of alternative shapes forthe spacers of FIG. 4 ;

FIG. 7 is a front elevational view of a fill sheet in accordance with asecond preferred embodiment of the present invention, which includes anintegrated drift eliminator at an air outlet side of the fill sheet;

FIG. 8 is a front perspective view of the fill sheet of FIG. 7 , takenfrom within shape 8-8 of FIG. 7 ;

FIG. 9 is a cross-sectional view of a portion of a pair of fill sheetsinstalled or assembled together to define a fill pack, taken along line9-9 of FIG. 7 and generally showing a flute of a drift eliminator andconnection of the drift eliminator flute to a cooling section of thefill sheets; and

FIG. 10 is a front elevational representation of a fill sheet inaccordance with a third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. Unless specifically set forth herein, theterms “a”, “an” and “the” are not limited to one element but insteadshould be read as meaning “at least one”. The words “right,” “left,”“lower,” and “upper” designate directions in the drawings to whichreference is made. The words “inwardly” or “distally” “front” or “rear”and “outwardly” or “proximally” refer to directions toward and awayfrom, respectively, the geometric center or orientation of the fillsheets or fill packs and related parts thereof. The terminology includesthe above-listed words, derivatives thereof and words of similar import.

It should also be understood that the terms “about,” “approximately,”“generally,” “substantially” and like terms, used herein when referringto a dimension or characteristic of a component of the invention,indicate that the described dimension/characteristic is not a strictboundary or parameter and does not exclude minor variations therefromthat are functionally the same or similar, as would be understood by onehaving ordinary skill in the art. At a minimum, such references thatinclude a numerical parameter would include variations that, usingmathematical and industrial principles accepted in the art (e.g.,rounding, measurement or other systematic errors, manufacturingtolerances, etc.), would not vary the least significant digit.

Referring to FIGS. 1-3C, a fill sheet, generally designated 10, inaccordance with a first preferred embodiment of the present inventionhas a heat transfer section 11, along with an air inlet portion 12,which may include an integral louver (not shown), an air outlet portion14, which may include an integral drift (See FIGS. 7-9 ), and/or otherstandard end features at the inlet portion 12 and/or the outlet portion14, as well as additional features, such as intermediate honeycombs. Thefill sheet 10 is not limited to including the integral louver or theintegral drift, neither of which are shown in the first preferredembodiment of the fill sheet 10, and may function without the louver anddrift or may include alternative features attached to, integrally formedwith, positioned adjacent to or abutting the air inlet and outletportions 12, 14, such as non-integral louvers and drift that abut, butare not integrally formed with the fill sheet 10. The air inlet portion12 of the first preferred fill sheet 10, which may include an integrallouver, is positioned at the air intake side 10 a of the sheet 10 andthe air outlet portion 14, which may include an integral drift, ispositioned at the air outlet side 10 b of the preferred cross-flow fillsheet 10.

The heat transfer section 11 of the first preferred fill sheet 10includes a herringbone-shaped microstructure 11 a or the microstructure11 a has a generally herringbone shape to increase the surface area ofthe fill sheet 10 in the heat transfer section 11 and provide mixing ofthe air and water during operation. The microstructure 11 a is notlimited to being comprised of the herringbone-shaped microstructure andmay be comprised of alternatively sized and shaped microstructure thatincreases the surface area of the fill sheet 10 in the heat transfersection 11 to expose additional water film area to the airflow. Themicrostructure 11 a preferably has a smaller microstructure height H_(s)when compared to the height of the macrostructure of the preferred fillsheet 10, wherein the macrostructure includes features such as theplurality of flutes 18, as is described in greater detail below. In thepreferred embodiments, the microstructure height H_(s) is threehundredths of an inch to one-half inch (0.03-0.5″) but is not so limitedand may fall outside this range depending on designer preferences,microstructure type, cooling tower type, expected loading and relateddesign considerations and preferences. The microstructure height Hs,however, of the preferred microstructure 11 a is within the preferredrange of the microstructure height H_(s) and is adaptable for use withthe preferred fill sheets 10.

The heat transfer section 11 of the fill sheet 10 also includes a spacer16, which may be comprised of pluralities of spacers 16. The spacers 16may be comprised of glue bosses, peg spacers or other similar structuresor features that space the fill sheets 10, 9 a, 9 b from each other inthe assembled or installed configurations. The spacers 16 preferablyextend from opposing front and rear surfaces of the fill sheet 10 andmate with opposing spacers 16 on adjacent fill sheets 10, but are not solimited and may be configured to extend from only a single surface ofthe fill sheet 10 or may be otherwise sized and configured to space thefill sheets 10 in the assembled configurations. The spacers 16 on theadjacent fill sheets 10 in an assembled configuration are alsopreferably comprised of mating glue bosses or peg spacers thatfacilitate spacing of the assembled fill sheets 10 relative to eachother. The spacers 16 are not limited to mating glue bosses or pegspacers and may be comprised of nearly any feature of the fill sheets 10that facilitates spacing of the adjacent fill sheets 10 relative to eachother in the assembled configuration, including suspension or hanging ofthe fill sheets 10 next to each other at predetermined spacing intervalsor distances during operation. The spacers 16 may assist in joining orbonding the adjacent fill sheets 10 together in the assembledconfiguration or may provide general spacing between the adjacent fillsheets 10 in the assembled configuration. The configuration andoperation of the spacers 16 are described in greater detail below. Thefill sheets 10 of the preferred embodiments may also include spacers 16with alignment or connection features 19 extending therefrom. Thespacers 16 preferably provide a surface for mating with a spacer 16 froman adjacent fill sheet 10 to appropriately space a first fill sheet 9 afrom a second fill sheet 9 b in the assembled or installedconfiguration. The alignment or connection features 19 preferablyfacilitate proper alignment of the first sheet 9 a relative to thesecond sheet 9 b and/or provide for engagement or connection of theadjacent fill sheets 10 in the assembled or installed configuration.

The heat transfer section 11 of the fill sheet 10 further includesflutes 18 arranged thereon that generally extend parallel orsubstantially parallel to a lateral axis 20 of the fill sheet 10. Thelateral axis 20 extends generally horizontally in an installedconfiguration of the fill sheets 10 and is oriented generallyperpendicular to a vertical axis 22. The flutes 18 preferably guide theairflow through the heat transfer area 11, generally along the lateralaxis 20 from the intake side 10 a to the outlet side 10 b.

The first preferred fill sheet 10 also includes an improved ribconfiguration for vertical and lateral rigidity and strength of the fillpacks in the assembled configuration, including intake side ribs 24 andoutlet side ribs 26 that extend generally parallel to the air intakeside 10 a and air outlet side 10 b, respectively. The intake side ribs24 and the outlet side ribs 26 are preferably integrally formed in thefill sheet 10 proximate the air intake side 10 a and the air outlet side10 b, respectively and adjacent to the heat transfer area 11 or withinthe heat transfer area 11. The intake side ribs 24 and the outlet sideribs 26 are described in greater detail below.

Referring to FIGS. 7-9 , in a second preferred embodiment, a fill sheet10′ has similar features to the first preferred fill sheet 10 and thesame reference numerals are utilized to identify similar or the samefeatures, with a prime symbol (′) utilized to distinguish the featuresof the second preferred embodiment from the first preferred embodiment.The second preferred fill sheet 10′ includes an integral drifteliminator 50 that improves upon known tube based integral drifteliminators (not shown) by introducing a blocking structure 100 toimprove drift performance, as is described greater detail below.

Referring to FIGS. 1 and 7 , in the first and second preferredembodiments, the fill sheets 10, 10′ are oriented in the cooling towerand configured at a forward lean or to have a pack angle Δ, Δ′ ofapproximately five to ten (5-10) degrees in order to offset the effectsof the crossing airflow on the vertically flowing water on the fillsheet surfaces during operation. As the water flows down the sheets 10,10′, generally parallel to the vertical axis 22, 22′, the air tends topush the water toward the air outlet side 10 b, 10 b′ of the fill sheets10, 10′ due to friction at the air-water interface. The fill sheets 10,10′, thereby lean into the direction of air flow, generally along thelateral axis 20, 20′ such that a top front corner of the fill sheets 10,10′ near the intersection of the air intake side 10 a, 10 a′ and a topedge 28, 28′ is positioned closest to the air inlet of the tower. Thelower front corner of the fill sheets 10, 10′ near the intersection ofthe air intake side 10 a, 10 a′ and a bottom edge 30, 30′ is the portionof the air intake side that is positioned furthest from the air inlet ofthe tower.

Referring to FIGS. 1-3C, the heat transfer area 11 of the fill sheet 10is comprised of the herringbone-shaped microstructure 11 a formed overthe flutes 18 and covers a majority of the interior of the fill sheet10. The geometry of the flutes 18 is generally comprised of individualflutes 18 oriented substantially in the air travel direction orgenerally parallel to the lateral axis 20. The fill sheets 10 alsopreferably include transition features 32, which may be comprised ofoffsets 32 in the flutes 18. The transition features 32 preferablyprovide a generally flat macrostructure extending generally parallel tothe vertical axis 22 or pitched by the pack angle Δ, Δ′ from thevertical axis 22. A first flute 18 of the plurality of flutes 18transitions from the flat section of the transition feature 32 to thearcuate macrostructure spaced from the transition feature 32 (See FIG.1C). The flat section preferably includes a rib or support 38 extendinggenerally parallel to the vertical axis 22 and a spacer 16 to providelateral support for the rib or support 38. The spacer 16 is preferablypositioned proximate the rib or support 38 to provide lateral supportfor the rib or support 38 and is not limited to being positioned in theflat section or transition feature 32 but is preferably positionedproximate the rib or support 38 to provide lateral support. The spacer16 is preferably comprised of a first plurality of spacers 16 along orat the offset 32, wherein each of the plurality of flutes 18 isassociated with or includes one of the first plurality of spacers 16positioned thereon at the offset, flat section or transition feature 32.The pluralities of spacers 16 of the first preferred fill sheet 10 arepositioned at each of the offsets 32 proximate the air intake side 10 a,proximate the air outlet side 10 b, and proximate the intermediatevertical ribs 38, respectively.

The preferred fill sheets 10 include several intermediate offsets 32 inthe flutes 18 where the peaks 36 of the flutes 18 transition to valleys34, and vice versa, generally along the air flow direction or thelateral axis 20. The offsets or transition features 32 are typicallypositioned proximate to the columns of spacers 16 such that two adjacentfill sheets 10, such as the first and second fill sheets 9 a, 9 b (FIGS.3-3C) may be connected together or positioned next to each other todefine a fill pack 8. The first preferred fill sheets 10 and the fillpack 8 of FIGS. 1C and 3-3C show the transition of the peaks 36 to thevalleys 34 and the valleys 34 to the peaks 36 on opposite sides of theoffsets or transition features 32 in the direction of the lateral axis20, thereby creating a generally parallel orientation of the adjacentfirst and second fill sheets 9 a, 9 b in the heat transfer area 11. Theposition of the offsets 32 in the air travel direction or generallyparallel to the lateral axis 20 is staggered between the adjacent firstand second fill sheets 9 a, 9 b for any given vertical position on thefill pack 8. By staggering the offsets 32, a majority of the profiles ofthe flutes 18 for the fill pack 8 is parallel (FIGS. 3C and 3D) to theadjacent first and second sheets 9 a, 9 b, while short segments of thefill pack 8 between sets of offsets 32 have an opposing profile oradjacent peaks 36 to valleys 34 in the offsets 32 of the adjacent sheets9 a, 9 b (FIG. 3B), thereby providing a location for spacers 16 to beincorporated into the design without significantly protruding into theairstream of the flutes 18 and contributing to pressure drop. This firstpreferred configuration of the flutes 18 provides an advantage overprior tube-based flute arrangements by allowing the majority of theprofiles of the flutes 18 of the fill pack 8 to remain generallyparallel to and between the adjacent sheets 9 a, 9 b, thereby reducingareas of restricted air flow between the peaks 36 and valleys 34 ofadjacent sheets 9 a, 9 b of the fill pack 8. The staggered offsets 32also create a short tube region within the fill pack 8, which offersstructural advantages over a flute design that only consists of parallelflute profiles. By providing short segments proximate the offsets 32where the flutes 18 are aligned into a tube configuration with the peaks36 and valleys 34 of the adjacent sheets 9 a, 9 b generally aligning inthe offsets 32, the lateral stiffness of the fill pack 8 is increased,without the need for large spacer features intruding into the airflowregion. In addition, the transition regions on either side of the tubestructure of the offsets 32 provide a generally flat section to addvertical ribs or supports, such as intermediate vertical ribs orsupports 38 without cutting through the profile of the flutes 18. Theintermediate vertical ribs or supports 38 strengthen the fill pack 8without significantly increasing the pressure drop across the fill pack8 between the air intake side 10 a and the air outlet side 10 b.

Referring to FIGS. 3 and 4-6 , in addition to the improved geometry ofthe flutes 18 in the fill pack 8 of the first preferred embodiments usedin the cross-flow fill design, improvements have been made to thespacers 16 used to space the adjacent fill sheets 9 a, 9 b apart todefine the fill packs 8. The first preferred embodiment of the spacers16 has a generally angled teardrop or raindrop shaped spacer 16, atleast in the heat transfer area 11 where the microstructure 11 a isformed on the fill sheets 10. In an installed configuration, a firstspacer 16 a of the first fill sheet 9 a mates with and is joined,positioned in facing engagement or positioned proximate to a secondspacer 16 b on the second, adjacent fill sheet 9 b to space the firstand second fill sheets 9 a, 9 b at a predetermined distance from eachother and may facilitate joining or connection of the adjacent fillsheets 9 a, 9 b. The preferred fill sheets 9 a, 9 b have a plurality ofspacers 16 that extend from both opposing faces of the fill sheets 9 a,9 b to mate with adjacent fill sheets 9 a, 9 b, 10 in the installedconfiguration. As a non-limiting example, the first preferred fillsheets 9 a, 9 b, 10 have three columns of fourteen (14) spacers 16proximate a middle of the fill sheets 9 a, 9 b, 10 along the offsets 32and the air intake and air outlet sides 10 a, 10 b, respectively. Thefill sheets 9 a, 9 b also include pluralities of spacers 16 positionedadjacent the air intake and air outlet sides 10 a, 10 b with thealignment or connection features 19 thereon. The three columns ofspacers 16 include an intermediate column of spacers 15 b, an air intakeside column of spacers 15 a and an air exit side column of spacers 15 c.In the first preferred embodiment, the air intake side column of spacers15 a is positioned at an air intake side offset 32, the intermediatecolumn of spacers 15 b is positioned at an intermediate offset 32 andthe air exit side column of spacers 15 c is positioned at an air exitside offset 32. The intermediate column of spacers 15 b is positionedbetween a first intermediate rib 38 a and a second intermediate rib 38 bat the intermediate offset 32. The first intermediate rib 38 a ispositioned between the intermediate column of spacers 15 b and the airintake side 10 a and the second intermediate rib 38 b is positionedbetween the intermediate column of spacers 15 b and the air exit side 10b. The fill sheets 9 a, 9 b, 10 are not limited to including thefourteen (14) spacers 16 in each of the columns of spacers 15 a, 15 b,15 c or to the specific locations shown in the preferred embodiments andmay include more or less spacers 16, depending on the size of the fillsheets 9 a, 9 b, 10, the expected loading on the fill sheets 9 a, 9 b,10, the expected environment, designer preferences and related factors.The fill sheets 9 a, 9 b, 10 may include nearly any number of spacers 16that facilitate spacing or joining of the adjacent sheets 9 a, 9 b, 10together in the installed configuration, are able to withstand thenormal operating conditions of the spacers 16 and perform the functionsof the spacers 16, as described herein.

In the first preferred embodiment, each of the spacers 16 includes agenerally wider and relatively semi-circular shaped head end 40 and anarrower tail end 42. The first spacer 16 a includes a first head end 40a and a first tail end 42 a and the second spacer 16 b includes a secondhead end 40 b and a second tail end 42 b. The head ends 40 and the tailends 42 define the teardrop or raindrop shape of the spacer 16, whereinthe tail ends 42, 42 a, 42 b are generally rounded, particularly incomparison to a traditional teardrop or raindrop shape. In the installedconfiguration, the head ends 40 of adjacent spacers 16 generally mateand provide surfaces for joining the spacers 16 and the tail ends 42extend away from each other in the installed configuration, generally toopposite sides of the vertical axis 22. The tail ends 42 of the firstpreferred embodiment extend away from the head ends 40 along a spaceraxis 17. In the first preferred embodiment, the first spacer 16 aincludes a first spacer axis 17 a and the second spacer 16 b includes asecond spacer axis 17 b. The first and second spacer axes 17 a, 17 bpreferably define first and second acute spacer angles Ωa, Ωb,respectively, with the lateral axis 20 that are approximately ten toeighty degrees (10-80°), but are not so limited and may take on nearlyany acute angle that facilitates performance of the functioning of thespacers 16 and withstands the normal operating conditions of the spacers16, such as within the range of approximately twenty to fifty degrees(20-50°) or approximately thirty-five degrees (35°). The first spaceraxis 17 a preferably extends at a first side of the vertical axis 22 andthe second spacer axis 17 b preferably extends at a second, oppositeside of the vertical axis 22, such that the first and second spacer axes17 a, 17 b extend at opposite sides of the vertical axis 22. Thisextension of the first and second spacer axes 17 a, 17 b at oppositesides of the vertical axis 22 results in the first and second tail ends42 a, 42 b being spaced from each other in an installed configurationsuch that cooling fluid generally does not collect at and bridge betweenthe first and second tail ends 42 a, 42 b, particularly if they were tosubstantially mate. The first spacer axis 17 a preferably extends from acentral portion of the first head end 40 a through a central portion ofthe first tail end 42 a and the second spacer axis 17 b preferablyextends from a central portion of the second head end 40 b through acentral portion of the second tail end 42 b, even if the first andsecond spacers 16 a, 16 b have some curvature to the tail ends 42 a, 42b and is not necessarily straight or uniformly shaped. The first andsecond spacer axes 17 a, 17 b also preferably define a separation angleμ measured between the first and second acute spacer angles Ωa, Ωbacross the vertical axis 22. The separation angle μ is preferablybetween approximately twenty and one hundred sixty degrees (20-160°),preferably approximately one hundred twenty degrees (120°). Theseparation angle μ plus the first and second spacer angles Ωa, Ωbpreferably sum to one hundred eighty degrees (180°).

In the first preferred embodiment, adjacent spacers 16, such as thefirst and second spacers 16 a, 16 b, are oriented with their tail ends42 a, 42 b extending in opposite directions or to opposite sides of thevertical axis 22, thereby forming an upside down V-shape when viewedfrom the front or rear (FIGS. 5 and 6 ). This mis-alignment of the tailends 42, 42 a, 42 b allows water, which hits the head ends 40, 40 a 40 bof the pair of spacers 16, 16 a, 16 b, to run down the sloped sidesurfaces of each of the spacers 16, 16 a, 16 b and separate near thetail ends 42, 42 a, 42 b of the spacers 16, 16 a, 16 b. In contrast,prior art glue bosses that fully align and have generally the same sizeand shape result in the water or other cooling fluid flowing over theprior art glue bosses and forming a film of water below the connection,which spans between the two associated fill sheets and impedes airflow.The inverted V shape formed by the tail ends 42, 42 a, 42 b of theadjacent spacers 16, 16 a, 16 b is the preferred shape to provide acontact surface to space adjacent fill sheets 10, 9 a, 9 b and toprevent water sheeting, while minimizing the height of the spacerprofile between the adjacent fill sheets 10, 9 a, 9 b of the fill packs8 in the waterflow direction or generally parallel to the vertical axis22. The preferred spacers 16 have the teardrop or raindrop shape, butthis shape is not limiting. For example, in an alternative preferredembodiment, the spacers 16 may have a generally rectangular shape (FIG.6 ), or any shape which forms a contact feature with an adjacent spacerfeature near the top of the connection, and slopes downward and awayfrom the adjacent spacer 16 relative to the vertical axis 22. Theadjacent spacers 16, 16 a, 16 b are preferably glued or otherwisesecured together, such as by ultrasonic welding or mechanical joining,at the mating surfaces in the installed configuration to connect thefill sheets 10, 9 a, 9 b together, thereby forming the fill packs 8. Thespacers 16, 16 a, 16 b are not limited to being glued or otherwisejoined together in the installed configuration and may act exclusivelyas spacers to space the adjacent fill sheets 10, 9 a, 9 b relative toeach other in the installed configuration, such as when the fill sheets10, 9 a, 9 b hang from a rail adjacent to each other in the tower, butare not otherwise joined or connected at the spacers 16, 16 a, 16 b. Inaddition, the spacers 16, 16 a, 16 b may include connection featuresthat secure the spacers 16, 16 a, 16 b together in the installedconfiguration or may be otherwise connected or joined together in theinstalled configuration, such as by ultrasonic welding, mechanicaldeformation, fastening or otherwise securing the mating spacers 16, 16a, 16 b together in the installed configuration.

Referring to FIGS. 1-3C, structural support is provided to the firstpreferred fill sheets 10, 9 a, 9 b and fill packs 8 by the intake sideribs 24, the outlet side ribs 26 and the intermediate vertical ribs orsupports 38, as well as the remaining body of the fill sheets 10, 9 a, 9b. Each of the intake and outlet side ribs 24, 26 and the intermediateribs 38 is preferably comprised of two substantially vertical supportribs 24 a, 24 b, 26 a, 26 b, 38 a, 38 b extending along the height ofthe fill sheet 10, 9 a, 9 b, generally parallel to the air intake side10 a and the air outlet side 10 b. In the first preferred embodiment,the support ribs 24 a, 24 b, 26 a, 26 b, 38 a, 38 b are not fullyvertical, but are oriented substantially parallel to the air intake andair outlet sides 10 a, 10 b of the fill sheets 9 a, 9 b, 10, such thatthe support ribs 24 a, 24 b, 26 a, 26 b, 38 a, 38 b are orientedgenerally at the pack angle Δ, Δ′ of approximately five to ten (5-10)degrees relative to the vertical axis 22, but are not so limited and maybe otherwise oriented and configured. The microstructure 11 a of theheat transfer area 11 of each of the fill sheets 10, 9 a, 9 b ispreferably comprised of angled bands of microstructure 11 a in theherringbone arrangement, extending between at least the first structuralintake and outlet side ribs 24 b, 26 a, respectively, in the heattransfer area 11. The preferred support ribs 24, 26, 38, including theintake side ribs 24, 24 a, 24 b, the outlet side ribs 26, 26 a, 26 b andthe intermediate ribs 38, 38 a, 38 b, extend generally vertically alongthe fill sheet 10, 9 a, 9 b in the installed configuration. The ribs 24a, 24 b, 26 a, 26 b, vary in height in an alternating pattern as theyextend along the fill sheet 10, 9 a, 9 b from and between the top edge28 and the bottom edge 30. In the preferred embodiment, the intake andoutlet side ribs 24 a, 24 b, 26 a, 26 b alternate between a maximumheight H_(x) and a minimum height H_(n). The pairs of first and secondintake side ribs 24 a, 24 b of the intake side rib 24, the first andsecond outlet side ribs 26 a, 26 b of the outlet side rib 26, and thefirst and second intermediate supports 38 a, 38 b of the intermediatesupport 38 are designed such that there is preferably at least one ribor support 24 a, 24 b, 26 a, 26 b, 38 a, 38 b with a height, such as therib maximum height H_(x) extending past or being greater than themicrostructure height H_(s) of the microstructure 11 a on any givenposition along the lengths of the individual ribs or supports 24, 26, 38on the fill sheets 10, 9 a, 9 b.

In the first preferred embodiment, the first and second air intake ribs24 a, 24 b are configured such that while the first air intake rib 24 ahas the maximum height H_(x) that extends past or is greater than themicrostructure height H_(s) of the microstructure 11 a and the secondair intake rib 24 b extends below or has the rib minimum height H_(n)that is less than the microstructure height H_(s) of the microstructure11 a. Similarly, the first and second outlet side ribs 26 a, 26 b areconfigured such that while the first outlet side rib 26 a has the ribmaximum height H_(x) that extends past or is greater than themicrostructure height H_(s) of the microstructure 11 a, the secondoutlet side rib 26 b has the rib minimum height H_(n) that dips below oris less than the microstructure height H_(s) of the microstructure 11 a.The first and second intermediate ribs or supports 38 a, 38 b aresimilarly configured in the first preferred embodiment in that the firstand second intermediate ribs 38 a, 38 b are laterally spaced, but aredifferently configured in that the first intermediate rib 38 asubstantially ends at a height where the second intermediate rib 38 bbegins. There may be sections where both of the first and second inletside ribs 24 a, 24 b, the first and second outlet side ribs 26 a, 26 band the first and second intermediate ribs or supports 38 a, 38 b aretaller than the surrounding microstructure 11 a to provide additionalsupport at the base of the fill sheets 10, 9 a, 9 b and fill packs 8,such as where the fill pack 8 meets the supporting structure underneaththe fill pack 8 in an assembled configuration in the tower. The airintake and outlet ribs 24, 26 are, however, preferably configured suchthat when one of the pair of first and second ribs 24 a, 24 b, 26 a, 26b, respectively, is at its greatest height relative to themicrostructure 11 a, the adjacent one of the pair of first and secondribs 24 a, 24 b, 26 a, 26 b, respectively, is at its smallest height oris generally below the height of the microstructure 11 a and issubstantially embedded in the microstructure 11 a. The first and secondribs 24 a, 24 b, 26 a, 26 b, therefore, have alternating tapers betweenthe top edge 28 and the bottom edge 30.

The intake side rib 24 and the outlet side rib 26 are not limited toextending from the top edge 28 to the bottom edge 30. The intake siderib 24 and the outlet side rib 26 may extend proximate to the top andbottom edges 28, 30 and may include some interruptions along theirlength, but the intake and outlet side ribs 24, 26 preferably extend tothe top and bottom edges 28, 30 and are comprised of the alternatelyextending pairs of first and second ribs 24 a, 24 b, 26 a, 26 b thatalternatively taper relative to each other. The intake and outlet sideribs 24, 26 extend to and between the top and bottom edges 28, 30 in thepreferred embodiments. The intake and outlet side support ribs 24, 26include the pairs of first and a second support ribs 24 a, 24 b, 26 a,26 b. The first and second support ribs 24 a, 24 b, 26 a, 26 b arespaced laterally from each other along the lateral axis 20 and extendsubstantially parallel to the vertical axis 22 or the intake and outletsides 10 a, 10 b. The intake and outlet side ribs 24, 26 have a firstsupport rib portion 33 having a first support rib length or firstsupport rib portion length L_(r1). The first support ribs 24 a, 26 ainclude a first rib height and the second support ribs 24 b, 26 binclude a second rib height. The first rib height is less than themicrostructure height in the first support rib portion 33 and the secondrib height is greater than the microstructure height in the firstsupport rib portion 33. The intake and outlet side ribs 24, 26 of thefirst preferred embodiment also have a second support rib portion 35having a second support rib length or second support rib portion lengthL_(r2). The first rib height is greater than the microstructure heightin the second support rib portion 35 and the second rib height is lessthan the microstructure height in the second support rib portion 35.

The intermediate rib 38 is alternatively constructed such that the firstintermediate rib 38 a extends from the top edge 28 approximately to amiddle of the vertical height of the fill sheet 10 where the firstintermediate rib 38 a substantially ends and the second intermediate rib38 b starts and extends to the bottom edge 30. The ribs 24, 26, 38 arenot limited to having these configurations and may be otherwise designedand configured to provide strength and stiffness to the fill sheet 10,such as switching the general configurations of the air intake andoutlet ribs 24, 26 and the intermediate ribs 38 or configuring each ofthe ribs 24, 26, 38 substantially the same.

By alternating the height or positioning of the pairs of first andsecond ribs 24 a, 24 b, 26 a, 26 b of the inlet side and outlet sideribs 24, 26 and the intermediate ribs 38 so that the localized height ofat least one of the pair of first and second ribs 24 a, 24 b, 26 a, 26b, 38 a, 38 b is preferably greater, specifically at the maximum heightH_(x), than the microstructure height H_(s) of the microstructure 11 afor any position along the length of the ribs 24, 26, 38 on the fillsheets 10, 9 a, 9 b, it is ensured that each side of the fill sheet 10,9 a, 9 b has at least one functioning stiffening member or rib 24, 26,38 for all vertical positions along the air intake side and the airoutlet side 10 a, 10 b, respectively, as well as in the intermediatearea or offset 32 between the intake and outlet sides 10 a, 10 b,thereby limiting weak points or sections where the fill sheets 10, 9 a,9 b may buckle. Additionally, the lower peak height sections of thepairs of first and second ribs 24 a, 24 b, 26 a, 26 b of the intake andoutlet side ribs 24, 26, wherein the maximum height H_(x) is present,allow the bands of overlapping microstructure 11 a to stiffen the fillsheet 10, 9 a, 9 b in the air travel direction or generally parallel tothe lateral axis 20 by creating minor corrugations which resist bendingmoment in the plane perpendicular to the applied force at the intake andoutlet side ribs 24, 26. This configuration increases the rigidity ofthe fill sheets 10, 9 a, 9 b for handling and shipping. Theconfiguration of the intake and outlet side ribs 24, 26 and theintermediate rib 38, wherein the full height rib sections or sectionswith the maximum rib height H_(x) overlap before transitioning to thelower height rib sections or sections with the minimum rib height H_(n)of the first and second ribs 24 a, 24 b, 26 a, 26 b, 38 a, 38 b,respectively, where load is transferred between the pairs of first andsecond ribs 24 a, 24 b, 26 a, 26 b, 38 a, 38 b of the intake and outletside ribs 24, 26 and the intermediate ribs 38 strengthens and also addssupport at the intake and outlet sides 10 a, 10 b and the intermediateportion of the fill sheets 10, 9 a, 9 b.

In the preferred embodiments, the maximum rib height H_(x) isapproximately four hundredths of an inch to three-quarters of an inch(0.04-0.75″) or approximately one hundredth of an inch to one-quarter ofan inch (0.01-0.25″) greater than the microstructure height H_(s). Themaximum rib height H_(x) of the stiffening members or ribs 24, 26, 38 isnot limited to these particular heights and may be otherwise sized andconfigured based on the expected loading of the stiffening member ribs24, 26, 38, external loading factors, designer preferences, size of thefill sheet 10, type of cooling medium employed and other designconsiderations. The maximum height H_(x) of the support ribs 24, 26, 38,however, preferably falls within the preferred range such that themaximum height H_(x) is greater than the microstructure height H_(s) indesired sections or segments while the minimum rib height H_(n) is lessthan the microstructure height H_(s) and the maximum rib height H_(x).In the preferred embodiments, the minimum rib height H_(n) isapproximately zero to one-half inch (0-0.5″) or smaller than themicrostructure height H_(s) of the particular fill sheet 10. The minimumrib height H_(n) of the stiffening members or ribs 24, 26, 38 is notlimited to these particular heights and may be otherwise sized andconfigured based on the expected loading of the stiffening member ribs24, 26, 38, external loading factors, designer preferences, size of thefill sheet 10, type of cooling medium employed and other designconsiderations. The minimum rib height H_(n) preferably falls within thepreferred range such that the minimum rib height is less than themicrostructure height H_(s) in desired sections or segments. Forexample, the minimum rib height H_(n) is about half or less than half ofthe microstructure height H_(s) and the microstructure height Hs isslightly greater than half the maximum rib height H_(x) in the firstpreferred embodiment (See FIG. 2D). The minimum rib height H_(n) mayalso be approximately zero, as is shown at the lower portion of thefirst intermediate rib 38 a and the upper portion of the secondintermediate rib 38 b of the first preferred fill sheet 10 (See FIG. 1).

In the first preferred embodiment, the first intermediate rib 38 aincludes a top intermediate rib end 39 a and a first intermediate ribend 39 b and the second intermediate rib 38 b includes a secondintermediate rib end 39 c and a third intermediate rib end 39 d. Thefirst intermediate rib end 39 b is positioned proximate the secondintermediate rib end 39 c on the fill sheets 10, 9 a, 9 b. The firstintermediate rib 38 a or the second intermediate rib 38 b is intersectedby the lateral axis 20 between the top intermediate rib end 39 a and thethird intermediate rib end 39 d, meaning the first intermediate rib 38 aor the second intermediate rib 38 b are intersected by the lateral axis20 at generally any location along the height of the fill sheets 10, 9a, 9 b between the top intermediate rib end 39 a and the thirdintermediate rib end 39 d. In the first preferred embodiment, thelateral axis 20 preferably intersects the first intermediate rib 38 a orthe second intermediate rib 38 b at any location between the top edge 28and the bottom edge 30, as the first intermediate rib 38 a generallyextends from the top edge 28 to a central portion of the fill sheet 10,9 a, 9 b and the second intermediate rib 38 b generally extends from thecentral portion of the fill sheet 10, 9 a, 9 b, where the firstintermediate rib end 39 b is positioned proximate the secondintermediate rib end 39 c, to the bottom edge 30. The first and secondintermediate ribs 38 a, 38 b are not limited to this preferredconfiguration and the first and second intermediate ribs 38 a, 38 b maybe separated into multiple segments, preferably such that at least oneof the segments of the first and second intermediate ribs 38 a, 38 b isintersected by the lateral axis 20 at generally any location along theheight of the fill sheets 10, 9 a, 9 b, as is described in furtherdetail below with respect to the intake and outlet side ribs 24, 26.

The first and second inlet and outlet side ribs 24 a, 26 a, 24 b, 26 bof the first preferred embodiment are comprised of a plurality of ribsegments 70 a, 70 b, 70 c, 70 d, 80 a, 80 b, 80 c, 80 d, wherein thefirst inlet side rib 24 a is comprised of a first inlet side rib segment70 a and a third inlet side rib segment 70 b, the second inlet side rib24 b is comprised of a second inlet side rib segment 70 c and a fourthinlet side rib segment 70 d, the first outlet side rib 26 a is comprisedof a first outlet side rib segment 80 a and a third outlet side ribsegment 80 b and the second outlet side rib 26 b is comprised of asecond outlet side rib segment 80 c and a fourth outlet side rib segment80 d. The first inlet side rib segment 70 a includes a top end 71 a anda first end 71 b and the third inlet side rib segment 70 c includes afourth end 71 e and a fifth end 71 f. The second inlet side rib segment70 b includes a second end 71 c and a third end 71 d and the fourthinlet side rib segment 70 d includes a sixth end 71 g and a seventh end70 h. The first outlet side rib segment 80 a includes a top end 81 a anda first end 81 b and the third outlet side rib segment 80 c includes afourth end 81 e and a fifth end 81 f The second outlet side rib segment80 b includes a second end 81 c and a third end 81 d and the fourthoutlet side rib segment 80 d includes a sixth end 81 g and a seventh end80 h. The inlet side rib 24 and outlet side rib 26 are configured suchthat at least one of the pluralities of segments 70 a, 70 b, 70 c, 70 d,80 a, 80 b, 80 c, 80 d is intersected by the lateral axis 20 at anyposition between the top ends 71 a, 81 a and the seventh ends 71 h, 81h, respectively. In contrast to the first and second intermediate ribs38 a, 38 b, the rib segments 70 a, 70 b, 70 c, 70 d, 80 a, 80 b, 80 c,80 d somewhat overlap in the height direction or the water flowdirection, such as between the third and fourth ends 71 d, 81 d, 71 e,81 e and the first and second ends 71 b, 81 b, 71 c, 81 c, for example.The rib segments 70 a, 70 b, 70 c, 70 d, 80 a, 80 b, 80 c, 80 d are notso limited and may be configured without the overlaps in the heightdirection and may include additional or less segments, althoughpreferably such that at least one of the rib segments 70 a, 70 b, 70 c,70 d, 80 a, 80 b, 80 c, 80 d of each of the inlet side rib 24 and theoutlet side rib 26, respectively, is intersected by the lateral axis 20at any position between the top and bottom edges 28, 30. The inlet sideribs 24, the outlet side ribs 26 and the intermediate ribs 38, includingthe respective rib segments 38 a, 38 b, 70 a, 70 b, 70 c, 70 d, 80 a, 80b, 80 c, 80 d, extend generally parallel to the vertical axis 22 or theintake and outlet sides 10 a, 10 b in the first preferred embodiment,but are not so limited and may be otherwise oriented and configured toprovide strength and stiffness to the fill sheets 9 a, 9 b, 10.

In the preferred embodiments, the inlet side rib 24, the outlet side rib26 and the intermediate rib 38 include the adjacent first and secondinlet side ribs 24 a, 24 b, the first and second outlet side ribs 26 a,26 b and the first and second intermediate ribs 38 a, 38 b,respectively. The pairs of the first and second inlet side ribs 24 a, 24b, the first and second outlet side ribs 26 a, 26 b and the first andsecond intermediate ribs 38 a, 38 b are spaced at a lateral spacingS_(L) that is preferably between one-quarter and two inches (¼-2″). Thelateral spacing S_(L) is not limited to being between one-quarter andtwo inches (¼-2″) and may be otherwise sized and configured based onfill sheet 10 loading, external loading factors, designer preferences,size of the fill sheet 10 and other design considerations. The lateralspacing S_(L) of the first and second outlet side ribs 26 a, 26 b isshown in FIG. 2 and the first and second inlet side ribs 24 a, 24 b andthe first and second intermediate ribs 38 a, 38 b are also similarlydesigned and configured to have the lateral spacing S_(L).

The inlet side rib 24 and the outlet side rib 26, including first andsecond inlet and outlet side ribs 24 a, 24 b, 26 a, 26 b and havevariable heights between the top and bottom edges 28, 30. As anon-limiting example, the outlet side rib 26 and, specifically, thesecond outlet side rib 26 b includes the second outlet side rib segment80 b and the fourth outlet side rib segment 80 d with a reduced heightportion or portion with the minimum rib height H_(n) of the secondoutlet side rib 26 b extending between the second outlet side ribsegment 80 b and the fourth outlet side rib segment 80 d between the topedge 28 and the bottom edge 30. The second outlet side rib segment 80 bpreferably has the rib maximum height H_(x) in the second outlet siderib segment 80 b and the fourth outlet side rib segment 80 d has the ribminimum height H_(n) in a portion between the second and fourth outletside rib segments 80 b, 80 d. The second outlet side rib 26 b of thepreferred embodiment also includes transition portions 110 where thesecond outlet side rib 26 b transitions between the rib maximum heightH_(x) and the rib minimum height H_(n) along the length of the secondoutlet side rib 26 b. Each of the intake side ribs 24, 24 a, 24 b andthe outlet side ribs 26, 26 a, 26 b are preferably similarly configuredto the second outlet side rib 26 b, with the rib segments or portionshaving the rib maximum height H_(x), portions or segments having the ribminimum height H_(n) and the transition portions 110 between thesegments with the rib maximum and minimum heights H_(x), H_(n). Inaddition, the pairs of intake side ribs 24 a, 24 b and outlet side ribs26 a, 26 b preferably have the transition portions 110 at generally thesame lateral positions along the lateral axis 20 and opposing ribmaximum and minimum heights H_(x), H_(n) along the lateral axis 20 forthe adjacent intake side and outlet side ribs 24 a, 24 b, 26 a, 26 b,respectively. As a non-limiting example, the second outlet side ribsegment 80 b preferably has the rib maximum height H_(x) along thelateral axis 20 while the adjacent portion or segment of the firstoutlet side rib 26 a has the rib minimum height H_(n).

The microstructure 11 a in the heat transfer section 11 of the preferredembodiment has a microstructure height H_(s). The minimum height orfirst rib height H_(n) is less than the microstructure height H_(s) in afirst rib support portion, such as along the intake side and outlet sideribs 24 a, 24 b, 26 a, 26 b wherein the ribs 24 a, 24 b, 26 a, 26 b havethe minimum height H_(n). The maximum height H_(x) is, conversely,greater than the microstructure height H_(s) in a second rib supportportion, such as along the intake side and outlet side ribs 24 a, 24 b,26 a, 26 b wherein the ribs 24 a, 24 b, 26 a, 26 b have the maximumheight H_(n). The ribs 24 a, 24 b, 26 a, 26 b are not so limited and mayhave consistently smaller or greater heights than the microstructureheight Hs, depending on design and requirement considerations of theparticular fill sheet 10. The ribs 24 a, 24 b, 26 a, 26 b are notlimited to the described configuration with the alternating maximum andminimum heights H_(x), H_(n) with the transition portions 110therebetween and the microstructure height H_(s) being between themaximum and minimum heights H_(x), H_(n) and may be otherwise designedand configured to support the fill sheets 10 based on designerpreferences, loads being carried by the fill sheet 10, external factorsof the operating environment or other factors that may drive the designand configuration of the intake side and outlet side ribs 24 a, 24 b, 26a, 26 b. The intermediate rib 38 may be similarly designed andconfigured as the intake side and outlet side ribs 24 a, 24 b, 26 a, 26b with the maximum and minimum heights H_(x), H_(n) and themicrostructure height H_(s) sized therebetween, but is similarly not solimited, as is described herein. In addition, in the preferredembodiments, the intake side and outlet side ribs 24 a, 24 b, 26 a, 26 band the intermediate rib 38 has a generally arcuate-shapedcross-section. The intake side and outlet side ribs 24 a, 24 b, 26 a, 26b and the intermediate rib 38 are not limited to having thearcuate-shaped cross-section and may have alternative cross-sectionalshapes, such as solid, squared, triangular or other shapes, as long asthe intake side and outlet side ribs 24 a, 24 b, 26 a, 26 b and theintermediate rib 38 are able to perform the preferred functions andwithstand the normal operating conditions of the intake side and outletside ribs 24 a, 24 b, 26 a, 26 b and the intermediate rib 38, as isdescribed herein.

The preferred intake side and outlet side ribs 24 a, 24 b, 26 a, 26 binclude the transition portions 110, which has a substantiallyconsistent first taper, therein the intake side and outlet side ribs 24a, 24 b, 26 a, 26 b transition from the minimum or first rib heightH_(n) to the maximum or second rib height H_(n). The transition portions110 are not limited to having the substantially consistent first taperand may have staged, stepped, sudden or otherwise inconsistent tapersbetween various heights along their length, but the preferred intakeside and outlet side ribs 24 a, 24 b, 26 a, 26 b have the relativelyconsistent first taper to assist in transitioning loads, formanufacturability, to limit stress concentrations and for additionaldesign considerations.

Referring to FIGS. 7-9 , in the second preferred embodiment, the fillsheet 10′ includes the integral drift eliminator 50. The integral drifteliminator 50 of the second preferred embodiment is comprised of anangled tube integral drift eliminator type, with a blocking structure orrib 100 at a drift eliminator inlet 102 where air flow enters the drifteliminator 50 from the heat transfer area 11′ of the fill sheet 10′ inthe fill pack 8′. The blocking structure 100 is substantially comprisedof a rib or wall in the preferred embodiment. The drift eliminator 50 isnot limited to including the blocking rib 100 or to the blockingstructure 100 being oriented generally vertically or to being a rib orwall. The blocking structure or rib 100 may be comprised of nearly anystructure that provides an impediment or block for cooling fluid flowingdirectly into the drift eliminator 50 and facilitates drip formation atthe inlet 102, preferably on or proximate to the blocking structure 100so that the cooling fluid drips do not form deep into the drifteliminator 50. The cooling fluid is then able to drain back into theheat transfer area 11′ before exiting the drift eliminator 50 and beinglost from the cooling tower.

The blocking structure 100 preferably provides a block to drift,typically comprised of cooled water droplets or cooling fluid, orformation of cooling fluid drips at the inlet 102 so that the coolingfluid does not flow deep into the drift eliminator 50. Formation ofdrips at the inlet 102 generally prevents the fluid from flowing deepinto the drift eliminator 50, potentially escaping into the drifteliminator 50 and out of the heat transfer area 11′. The cooling fluidcaptured at the inlet 102 of the drift 50 is preferably, ultimatelymaintained in the heat transfer area 11′ for further disappation of heatand eventually into a catch basin (not shown) below the fill pack 8′ orthe individual fill sheets 9 a, 9 b, 10 in the tower (not shown). Toprevent the cooled water or cooling fluid film that is flowing throughthe fill pack 8′ from travelling up and out of the tubes 104 of thedrift eliminator 50 and out of the air outlet side 10 b′ of the fillpack 8′, the blocking structure 100 is added at the drift eliminatorinlet 102 which acts as a barrier for the water film and a dripformation area to limit flow of the cooling fluid deep into the drift50. As the water or cooling fluid film reaches the blocking structure100, the film forms drips which enter the airstream near the drifteliminator inlet 102, rather than farther into the drift eliminator tube104 toward the air outlet side 10 b. This change in the location of dripformation at the drift eliminator inlet 102 on the blocking structure100 causes the droplet or drip to be introduced to the air stream in alocation earlier in the transition of airflow direction, thereby causingthe droplet or drip to impact a bottom tube wall of the drift eliminatortubes 104. The drip from the drift eliminator inlet 102 is therebyremoved from the airstream to improve performance and effectiveness ofthe drift eliminator 50 and the fill pack 8′, because the potentiallylost cooled water or other cooling fluid film is blocked at the blockingrib 100 to facilitate drip formation at the inlet 102 to be captured bythe drift eliminator tubes 104. The water or cooling fluid, therefore,flows back into the heat transfer area 11′ through a drainage structure106 for further disappation of heat and eventually into the catch basinbelow the fill pack 8′ during operation. In the second preferredembodiment, the blocking structure 100 is comprised of a pair of roundedribs or walls measuring from approximately five hundredths of an inch totwo tenths of an inch (0.05″-0.2″) in height and one tenth to one-halfinch (0.1″-0.5″) in width. The blocking structure or ribs 100, which areformed at the drift eliminator inlets 102 of each of the fill sheets10′, 9 a′, 9 b′, align generally adjacent the top walls of each of thedrift eliminator inlets 102 of the tubes 104 to act as a barrier for thewater film to generally limit the water or other cooling fluid driftfrom moving into the tubes 104 or facilitate formation of drips to limitflow of the cooling fluid deep into the drift 50.

The second preferred embodiment of the fill sheet 10′ also includesdrainage structures 106 (FIG. 8 ) positioned inwardly toward a center ofthe sheet 10′ relative to the drift eliminator 50. The drainagestructures 106 provide a flowpath for the water or cooling fluid blockedby the blocking structure 100 to flow back into the heat transfer area11′ for further dissipation of heat. The second preferred fill sheet 10′is not limited to inclusion of the drainage structure 106 and mayinclude alternatively configured features to direct the captured wateror other cooling fluid back into the heat transfer area 11′ or nofeatures without significantly impacting the structure and operation ofthe second preferred fill sheet 10′.

Referring to FIG. 10 , in a third preferred embodiment, a fill sheet 10″has similar features compared to the first and second preferred fillsheets 10, 10′ and the same reference numerals are utilized to identifysimilar or the same features, with a double prime symbol (″) utilized todistinguish the features of the third preferred embodiment from thefirst and second preferred embodiments. The third preferred fill sheet10″ includes an intermediate rib 38″ including first, second and thirdintermediate ribs 38 a″, 38 b″, 38 c″. Each of the first, second andthird intermediate ribs 38 a″, 38 b″, 38 c″ are laterally spaced fromeach other and include intermediate rib segments 90 a, 90 b, 90 c, 90 d,90 e, 90 f, 90 g that extend generally vertically or parallel to thevertical axis 22″ to provide strength and stiffness to the thirdpreferred fill sheet 10″.

In the third preferred embodiment, the first intermediate rib 38 a″includes first and third intermediate rib segments 90 a, 90 c, thesecond intermediate rib 38 b″ includes second, fourth and fifthintermediate rib segments 90 b, 90 d, 90 e and the third intermediaterib 38 c″ includes sixth and seventh intermediate rib segments 90 f, 90g. The first intermediate rib segment 90 a includes top and first ends91 a, 91 b and the second intermediate rib segment 90 b includes secondand third ends 91 c, 91 d. The first end 91 a of the first intermediaterib segment 90 a is positioned proximate the second end 91 c of thesecond intermediate rib segment 90 b such that at least one of the firstand second intermediate ribs 90 a, 90 b is intersected by the lateralaxis 20″ between the top end 91 a and the third end 91 d, meaning thereis generally not an interruption of the first and second intermediaterib segments 90 a, 90 b where the lateral axis 20″ would not intersecteither the first or the second intermediate rib segment 90 a, 90 bbetween the top end 91 a and the third end 91 d. All of the plurality ofintermediate rib segments 90 a, 90 b, 90 c, 90 d, 90 e, 90 f, 90 g aresimilarly arranged and configured such that the lateral axis 20″intersects at least one of the plurality of intermediate rib segments 90a, 90 b, 90 c, 90 d, 90 e, 90 f, 90 g between an end of the intermediaterib segment that is closest to the top edge 28″ of the fill sheet 10″,which is a tenth end 91 k of a sixth intermediate rib segment 90 f inthe third preferred embodiment, and an end of the intermediate ribsegment that is closest to the bottom edge 30″, which is a fifth end 91f of a third intermediate rib segment 90 c in the third preferredembodiment. In the third preferred embodiment, the third intermediaterib segment 90 c includes a fourth end 91 e and a fifth end 91 f, thefourth intermediate rib segment 90 d includes a sixth end 91 g and aseventh end 91 h, the fifth intermediate rib segment 90 e includes aneighth end 91 i and a ninth end 91 j, the sixth intermediate rib segment90 f includes a tenth end 91 k and an eleventh end 91 l and the seventhintermediate rib segment 90 g includes a twelfth end 91 m and athirteenth end 91 n. To maintain strength and stiffness of the thirdpreferred intermediate rib 38″ the tenth end 91 k is positionedproximate the top end 28″, the eleventh end 91 l is positioned proximatethe eighth end 91 i, the ninth end 91 j is positioned proximate the topend 91 a, the first end 91 b is positioned proximate the second end 91c, the third end 91 d is positioned proximate the twelfth end 91 m, thethirteen end 91 n is positioned proximate the sixth end 91 g, theseventh end 91 h is positioned proximate the fourth end 91 e and thefifth end 91 f is positioned proximate the bottom edge 30″. The thirdpreferred intermediate rib 38″, therefore, extends generally verticallyor parallel to the vertical axis 22″ or to the intake and outlet sides10 a, 10 b such that the lateral axis 20″ intersects at least one of theplurality of intermediate rib segments 90 a, 90 b, 90 c, 90 d, 90 e, 90f, 90 g between the tenth end 91 k and the fifth end 91 f. The sixthintermediate rib segment 90 f and the third intermediate rib segment 90c are spaced from the top and bottom edges 28″, 30″, but are not solimited and may extend to the top and bottom edges 28″, 30″ or closer tothe top and bottom edges 28″, 30″, respectively.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed but isintended to cover modifications within the spirit and scope of thepresent invention as defined by the present disclosure.

1-20. (canceled)
 21. A fill sheet for assembly into fill packs comprisedof pluralities of fill sheets, the fill sheet comprising: an air intakeend; an air outlet end positioned opposite the air intake end along alateral axis; a top edge connecting the air intake end and the airoutlet end; a bottom edge connecting the air intake end and the airoutlet end, the bottom edge positioned opposite the top edge along avertical axis; an outlet side rib including a first outlet side ribsegment having a top end and a first end and a second outlet side ribsegment having a second end and a third end, the top end positionedproximate the top edge, the outlet side rib extending substantiallyparallel to the vertical axis, the first outlet side rib segment beinglaterally spaced from the second outlet side rib segment by a lateralspacing, the first outlet side rib segment overlapping with the secondoutlet side rib segment between the first end and the second end suchthat the first and second outlet rib segments are intersected by thelateral axis between the first end and the second end; and an inlet siderib including a first inlet side rib segment having a top end and afirst end and a second inlet side rib segment having a second end and athird end, the top end of the first inlet side rib segment positionedproximate the top edge, the first inlet side rib segment being laterallyspaced from the second inlet side rib segment by a lateral spacingbetween the first inlet side rib and the second inlet side rib, thefirst inlet side rib segment overlapping with the second inlet side ribsegment between the first end of the first inlet side rib segment andthe second end of the second inlet side rib segment such that the firstand second inlet side rib segments are intersected by the lateral axisbetween the first end of the first inlet side rib segment and the secondend of the second inlet side rib segment.
 22. The fill sheet of claim21, wherein the lateral spacing is between one-quarter and two inches.23. The fill sheet of claim 21, wherein the outlet side rib is orientedat a pack angle relative to the vertical axis.
 24. The fill sheet ofclaim 23, wherein the pack angle is zero to ten degrees.
 25. The fillsheet of claim 21, wherein the outlet side rib further includes a thirdoutlet side rib segment and a fourth outlet side rib segment, the thirdoutlet side rib segment vertically aligned with the first outlet siderib segment and the fourth outlet side rib segment vertically alignedwith the second outlet side rib segment, the inlet side rib furtherincludes a third inlet side rib segment and a fourth inlet side ribsegment, the third inlet side rib segment vertically aligned with thefirst inlet side rib segment and the fourth inlet side rib segmentvertically aligned with the second inlet side rib segment.
 26. The fillsheet of claim 21, wherein the first and second outlet side rib segmentsand the first and second inlet side rib segments have a generallyarcuate-shaped cross-section.
 27. The fill sheet of claim 21, wherein aninterior section of the fill sheet includes a herringbone-shapedmicrostructure.
 28. The fill sheet of claim 27, wherein the interiorsection is a heat transfer section and the heat transfer sectionincludes a plurality of flutes extending through the heat transfersection and oriented to guide airflow in the heat transfer sectiongenerally along the lateral axis;
 29. The fill sheet of claim 21,further comprising: an air exit side column of spacers positionedproximate the outlet side rib, the outlet side rib positioned betweenthe air outlet end and the air exit side column of spacers.
 30. The fillsheet of claim 21, further comprising: a transition feature orientedgenerally parallel to the vertical axis and positioned centrally betweenthe air intake end and the air outlet end.
 31. The fill sheet of claim21, further comprising a honeycomb portion oriented generally parallelto the vertical axis and positioned proximate the air outlet end, theoutlet side rib positioned in the honeycomb portion, the honeycombportion oriented to direct working fluid toward a central portion of thefill sheet.
 32. A fill sheet for assembly into fill packs comprised ofpluralities of fill sheets, the fill sheet comprising: an air intakeend; an air outlet end positioned opposite the air intake end along alateral axis; a top edge connecting the air intake end and the airoutlet end; a bottom edge connecting the air intake end and the airoutlet end, the bottom edge positioned opposite the top edge along avertical axis; an inlet side rib extending generally parallel to thevertical axis proximate the air intake end, the inlet side rib includinga first inlet side rib segment and a second inlet side rib segmentspaced laterally from the first inlet side rib segment at a lateralspacing, the first inlet side rib segment overlapping with the secondinlet side rib segment between a first end of the first inlet side ribsegment and a second end of the second inlet side rib segment such thatthe first and second inlet side ribs are intersected by the lateral axisbetween the first and second ends of the first inlet side rib segment;an outlet side rib extending generally parallel to the vertical axisproximate the air outlet end; and a transition feature orientedgenerally parallel to the vertical axis and positioned centrally betweenthe air intake end and the air outlet end.
 33. The fill sheet of claim32, wherein the outlet side rib is comprised of a plurality of outletside rib segments, including first, second, third and fourth outlet siderib segments.
 34. The fill sheet of claim 33, wherein the first andthird outlet side rib segments are vertically aligned and laterallyspaced from the second and fourth outlet side rib segments by a lateralspacing.
 35. The fill sheet of claim 32, wherein the first and thirdinlet side rib segments are vertically aligned and the second and fourthinlet side rib segments are vertically aligned, the first and thirdinlet side rib segments spaced laterally relative to the second andfourth inlet side rib segments.
 36. The fill sheet of claim 32, whereinthe outlet side rib is positioned between an air exit side column ofspacers and a plurality of air outlet end spacers, the exit side columnof spacers positioned in an interior section of the fill sheet and theair outlet end spacers positioned outside the interior section of thefill sheet.
 37. The fill sheet of claim 36, wherein the exit side columnof spacers has a different configuration than the air outlet endspacers.
 38. The fill sheet of claim 32, further comprising: a honeycombportion oriented generally parallel to the vertical axis and positionedproximate the air outlet end, the outlet side rib positioned in thehoneycomb portion, the honeycomb portion oriented to direct workingfluid back into an interior section of the fill sheet.
 39. The fillsheet of claim 38, wherein the interior section includes aherringbone-shaped microstructure.
 40. The fill sheet of claim 32,further comprising: a plurality of flutes in an interior section of thefill sheet to guide airflow between the air intake end and the airoutlet end.
 41. The fill sheet of claim 32, further comprising: an airintake side column of spacers positioned proximate the air intake end;and a plurality of air intake end spacers, the inlet side rib positionedbetween the air intake side column of spacers and the air intake endspacers.
 42. The fill sheet of claim 32, further comprising: an intakehoneycomb portion oriented generally parallel to the vertical axis andpositioned proximate the air intake end, the inlet side rib positionedin the intake honeycomb portion, the intake honeycomb portion orientedto direct working fluid back into an interior section of the fill sheet.43. The fill sheet of claim 32, wherein the inlet side rib, the outletside rib, the air intake end, and the air outlet end are oriented at apack angle relative to the vertical axis, the pack angle being zero toten degrees.